TH350 kick down question

[VF101_jay]

Hi all, I have a TH350 auto behind a 350ci chevy, the trans works good for the most part, and I think I have the cable for the throttle activated downshift hooked up correctly, but even applying full throttle when in third gear at a slow speed, the trans will not shift down on it's own. I dont think there is anything seriously wrong with the trany as it will shift down if I do it manually or if I slow to the set downshift point or stop, it shifts fine. The trans shifts up properly and shows no other signs of malfunction. Where should I start looking to figure this out. I should point out that I have little knowledge of the internals of an auto trans, so you may have to explain it to me SLOWLY.

Thanks, Jason